Leetcode #70: Climbing Stairs

Leetcode_0070.cpp

class Solution {
public:
    int climbStairs(int n) {
        vector<int> dp(n+1);
        dp[1] = 1;
        dp[2] = 2;
        for (int i=3; i<=n; i++) {
            dp[i] = dp[i-1] + dp[i-2];
        }
        return dp[n];
    }
};
// Note: Space complexity of this solution can be reduced to O(1) by using 2-3 variables instead of an array/vector. 
// As this generates a Fibonacci series, you can use a relatively more complex but efficient way of finding Nth Fibonacci number instead of using the dynamic programming approach.